This invention relates first of all to fluid spraying apparatus and more particularly to an improved, portable, self-contained viscous liquid spraying apparatus incorporating a new and improved pumping system for pumping the viscous liquid out through the spray applicator. By way of example, the pumping arrangement invented and disclosed herein can provide an improved pumping arrangement for the mobile spray apparatus disclosed in U.S. Pat. No. 4,311,274 of a common assignee to the instant invention. The pump assembly of the instant invention is especially adapted to spray the asphaltic emulsions and coal-tar-pitch emulsions mixed with sand and disclosed and discussed in U.S. Pat. No. 4,311,274. Secondly, invented and disclosed herein is an improved vertical lift double acting piston pump that reciprocates by utilizing alternate acting magnetically responsive switches to achieve reciprocation and incorporates an unique control mechanism comprising a combination electric and hydraulic network.